Boat and propulsion means therefor



Aug. 27, 1963 H. J. SNOW 3,101,592

BOAT AND PROPULSION MEANS THEREFOR Filed Nov. 14, 1960 3 Sheets-Sheet 1F|G 2 INVENTOR.

HAL J. SNOW xmm ATTORNEY Aug. 27, 1963 H. J. SNOW 3, 1,

BOAT AND PROPULSION MEANS THEREFOR Filed Nov. 14. 1960 3 Sheets-Sheet 2INVENTOR. HAL J. SNOW ZM //%M ATTORNEY Aug, 27, 1963 H. J. SNOW3,101,692

BOAT AND PROPULSION MEANS THEREFOR Filed Nov. 14, 1960 3 Sheets-Sheet 3I N VEN TOR. HAL J. SNOW BY M/MM ATTORNEY United States Patent 3,101,692BOAT AND PRGPULSIUN MEANS THEREFGR Hal J. Snow, 2610 S. Hillside,Wichita, Kans. Filed Nov. 14, 1960, Ser. No. 69,166 4 Claims. (Cl.11461) This invention relates to boats and to drive means tor a boat. Ina more specific aspect, this invention relates to a twin hulled boathaving specific novel and inventive drive means therefor. In anotherspecific aspect, the invention relates to a new boat construction havinga venturi configuration. In a still further specific aspect, theinvention relates to new sculling drive means. in another specificaspect, the invention relates to a drive means and boat, particularly atwin hulled boat having a venturi throat therebetween. Still morespecifically the invention rel-ates to novel drive means in combinationwith a novel boat construction.

Various types of boat constructions. and drive means therefor are knownin the prior art. The prior art boat constructions include twin hulledvessels having common drive means therefor. The twin hulled boats of theprior art represent a decided nnprovernent over previous single hulledboats in their stability and ease of operation. The prior twin huiledvessels have failed to provide the optimum shape or contour to the bullsto provide efiicient and streamlined movement of the boat through thewater.

The prior art drive means include the so-called sculling or cycloidaldrive means. These prior art pro pulsion drive means have not provedadequate or satisfactory and as a result thereof the potentialcommercial market for these drive means have not been realized.Furthermore, these prior art drive means have not been utilized withtwin rhulled boats to provide a highly desirable combination ofstructures.

The boat of the invention is of a twin hu'lled construction. In onepreferred specific embodiment of the invention, the twin hulls arepreferably contoured at one end portion so as to provide a venturiconfiguration therebetween. The other end portion of each of the hullsis preferably provided with steering rudders which are interconnected soas to move in unison. The drive means for the boat is preferably mountedso as to be in the entry and outlet portions adjacent the throat portionof the venturi passage to provide optimum efiiciency in driving theboat. In another preferred specific embodiment of the boat of theinvention the twin hulled construction is contoured so as to provide aventuri configuration at each end portion of the boat. A plurality ofpropulsion means can be provided for this boat construction preferablytwo are provided with one of the propulsion means mounted in each of theventuri entry and outlet portions formed by the inner hull lines. Thepropulsion means in each embodiment can be constructed so as to bemovable to change the direction of thrust to provide steering for theboat, or suitable rudders can be provided on the boat to steer same. Thestructure connecting the hulls in both embodiments can conveniently beeither a generally flat deck, or it can be formed of a wafiie orhoneycomb like structure and can have suitable superstructure mountedthereon to close in the deck, as desired.

The sculling or cycloidal type drive means of the invention preferablyincludes a generally cylindrical housing supported by a center shaft orpost carried by the boat. The housing preferably has a plurality ofpaddles. journaled in the housing. Suitable power means, such as agasoline engine or a powered electric generator and electric motor canbe provided to rotate the cylindrical housing while the center shaftremains stationary. Gearing preferably carried by the housing will causethe paddle shafts to rotate the paddles as the housing turns. The

2 sculling or cycloida-l drive means is preferably utilized with theboat construction having a vent-uri at each end portion thereof, and thesculling propulsion means is desirably mounted in the throat portion ofeach venturi.

Accordingly, it is an object of invention to provide a new boatconstruction.

A further object of the invention is to provide a new, novel andpractical means. for driving a cycloidal or sculling propeller.

Another obiect of the invention is to provide a new twin hulled boatconstruction.

A further object of the invention is to provide a new water craft havingincreased stability. 7

Another object is to provide a new water craft capable of operating inrelatively shallow Water.

A still further object-of the invention is to provide a new hulled boatconstruction wherein the bulls are contoured to form a venturi.

Another object of the invention is to provide a new boat constructionhaving a venturi passage with drive means mounted in the end portions ofthe venturi passage.

Another object of the invention is to provide a new boat constructionhaving a venturi hull line with sculling drive means mounted in endportions of the venturi passage. 7

Another object of the invention is to provide a new sculling drive meansfor a boat.

A further object of the invention is to provide a new sculling drivemeans particularly suitable for use in a twin hulled boat having aventuri passage formed therebetween with end portions in which thesculling drive means is received.

Another object is to provide a new water craft constructed to eliminatepower losses normally encountered in prior 2ft constructions.

A further object of the invention is to provide a water craft havingpropulsion means operable in the draft of the craft.

Various other objects, advantages and features of the invention willbecome apparent from the following description, taken in connection withthe accompanying drawings, in which: i

FIG. 1 is an isometric view of one preferred specific embodiment of the,boat of the invention having the sculling drive means of the inventionmounted therein.

FIG. 2 is an enlarged cross section view taken along the line 22 ofFIG. 1. 7

FIG. 3 is a diagrammatic view of the steering apparatus preferablyemployed with the boat and drive means of FIG. 1.v

FIG. 4 is a cross section View through the housing of the sculling drivemeans of the invention.

FIG. 5 is a top plan view of the housing of the sculling drive meansshowing the relative position of the various paddles and the connectionof the steering apparatus to the drive means.

FIG. 6 is an isometric view showing a preferred construction of thepaddles used with the sculling drive means.

FIG. 7 is an enlarged partial cross sectionview taken along the lines 77of FIG. 5. a

The following is a discussion and description of preferred specificembodiments of the boat of the invention and of the new drive means ofthe invention such being made with reference to the drawings Whereon thesame reference numerals are used to indicate the same or similar partsand/or st-ructure. It is to be understood that such discussion anddescription is not to unduly limit the scope of the invention.

Referring now to the drawings in detail, FIGS. 1 and 2 show a preferredspecific embodiment of the boat of the invention. The boat includes twohulls or frames 12 and 14. The hulls 12 and 14 are preferably hollow andare desirably formed of a molded plastic material which can be suitablyreinforced to provide the required strength. The hulls 12 and 14 arepreferably open at the top side to be secured to the boat deck in anysuitable manner. Hulls 12 and 14 can be filled with a foam material orother types of buoyant material to enhance the floatation qualities ofthe hulls or frames, and they can be divided into a plurality ofsections which are water tight so that if one section of the hull ispunctured or ruptured in use the boat will remain afloat until repairscan be made. The facing surfaces 16 and 18 of hulls l2 and 14respectively are preferably disposed in generally vertical planes andthe outer surfaces 20 and 22 are preferba-ly tapered slightly from thetop to the bottom of each hull to increase the stability and flotationof the boat.

A boat deck of any suitable construction can be pro vided on which thehulls are mounted. The deck shown in FIG. 1 is composed of threesections 24, 26 and 28. Each of the sections 24, 26 and 28 arepreferably constructed of a waflle or honeycomb type construction havingupper and lower panels 30 and 32 respectively separated by reinforcingribs 34. The panels 30 and 32 and ribs 34 can be of any suitableconstruction, including plastics, wood, light weight metals and thelike. The space between panels 30 and 32 can be filled with a foammaterial, if desired. The deck sections 24 and 28 are duplicates of eachother and can be separately constructed as shown in the drawings andhave the drive means mounted thereon and then be mounted .on the hullsin mirror image relation. In some instances, it will be desirable toform the entire deck structure of a single unitary deck instead of insections as shown. The deck sections can be spaced as shown and coveredwith suitable flooring material, or they can be in contact to form acontinuous deck.

When hulls 12 and 14 are mounted on or beneath deck sections 24, 26 and28 they are in generally parallel and spaced relation. The hulls 12 and14 when mounted on like passageway 38 between the hulls and having atoured as shown at 38 so as to form a venturi or venturilike passageway38 between the bulls and having a straight throat portion 38" withdiverging end portions 39 extending therefrom at each end of the boat.And, the passageway for water overall from end to end has been found tofunction in the manner of a venturi relative to the boat and movementthrough the water. The ends of each hull can also betapered from top tobottom as shown at 40 to reduce the friction at the leading edge of theboat.

Sculling or cycloid-al type propelling means, shown generally at 50, arepreferably provided and are preferably mounted in each end portion ofthe deck in sections 24 and 28 and positioned in relation to the hulls12 and 14 so as to be approximately in the enlarged or diverging endportions 39 adjacent ends of the throat of the venturi passage formed bythe hulls. The combination of the boat construction shown in FIG. 1 andthe sculling drive means therefor has been found to be very desirable inuse, the hull construction providing streamlined movement in the water.The sculling drive or propelling means of the invention is shown indetail in FIGS. 4-7.

The sculling propelling means includes a housing 52 preferablypositioned below one of the panels 30 of the deck. A center shaft 54,which is normally stationary, is suspended from the deck panel 30 orother portion of the craft in any suitable manner, such as by a collar56 being rigidly secured to the upper end portion of the shaft 54 toengage the panel 30. Shaft 54 is provided with another collar 58, FIG.7, which limits downward movement of the housing 2. The housing 52 ispreferably closed by a top 60 and a bottom 62, and suitable bearings 64and 66 can be provided to rotatably mount the housing 52 on shaft 54.Housing 52 is preferably cylindrical.

Drive shafts 68 are provided and are preferably j'ournaled in the top 60and bottom =62 of housing 52 and project downwardly therefrom as bestseen in FIG. 7. Preferably, a plurality of the drive shafts 68 areprovided, three of such being shown in the drawings, although more orless can be provided if desired. The drive shafts 68 are preferablyequally spaced from the center shaft 54 and equally spacedcircumferentially within the housing 52 The drive shafts 63 arepreferably journaled in the housing 52 by bearings 69 and 70. A collar72 can be secured to each drive shaft 63 to prevent upward movement ofthe shafts 68 within housing 52. A paddle 74 is secured to the lower endportion of each of the drive shafts 68. A preferred construction ofpaddle 74 is best seen in FIG. 6 wherein two plates 76 and 78 arepositioned on opposite sides of the shaft 68 and are secured togetherand to the shaft along the edges and in the center by welds, mountingbolts or the like. Preferably, the paddle tapers inwardly from top tobottom as shown in the drawings. The plates 76 and 78 can be formed ofmetal, wood, plastics and the like. As best seen in FIG. 5, the paddles74 are preferably mounted so that the planes of the paddles willintersect at a common point.

Intermediate shafts 80 are provided and are journaled in the housing 52by bearings 82 and 84 and positioned therein by a collar 86. One of theintermediate shafts 80 is provided for each of the drive shafts 68, andthe shafts 80 are positioned between the center shaft 54 and each of thedrive shafts 68.

Center shaft 54 has a sun gear keyed or otherwise secured thereto nearthe bottom 62 of the housing. The drive shafts 68 have planet gears 92secured thereto and the intermediate shafts 80 have gears 94 securedthereto. The gear ratio is such that the drive shafts 68, gears 92 andpaddles 74 rotate 180 degrees in one direction as the entire housing 52is rotated 360 degrees in the opposite direction. In order to facilitatelubrication of the gearing system, the housing 52 can be partially orwholly filled with a lubricant, such as grease or oil shown as at 96. Ifdesired, water can be used as a lubricant.

A plurality of wheels or rollers 98, preferably three in number, areprovided to engage the side of the housing 52 and support same duringrotation-of the housing. The wheels or rollers 98 are rotatably mountedwithin the deck structure in any suitable manner (not shown). In someinstances, it will be desirable to taper the side of the housing 52 fromtop to bottom and mount wheels or rollers 98 at an angle to provide thevertical support for the housing.

Suitable power means, such as the gasoline engines shown at 100, FIG. 1are provided and are mounted on the deck sections 24 and 28 withv thedrive shaft thereof projecting into the deck sections. The drive shaftof the engine is shown at 102 in FIG. 5 and has a pulley 104 securedthereto. A V-belt W6 is provided and connects the pulley 104 on thedrive shaft 102 of engine with the outer cylindrical surface :of thehousing 52 as shown in FIGS. 4, 5 and 7. In some instances, it will bedesirable to provide a generator on the deck structure to providecurrent for an electric motor which in turn drives V-belt 106.

In operation, when the gasoline or other type power means 100 is inoperation, pulley 104 will be turned driving V-belt 106 and causing thehousing 52 to be rotated about the stationary center shaft 54. Ashousing 52 rotates about shaft 54 the planetary gearing 90, 92 and 94Will cause the paddles 74 to be rotated, driving the boat in the water.As the boat moves in the water, the hulls forming the venturi willpermit streamlined movement of the boat relative to the water, thusproviding a highly eflicient boat having a relatively small amount ofenergy losses, and the advantage of the venturi structure will begain-ed to propel the boat.

As will be seen from FIG. 5, as the housing 52 is rotated drivingpaddles 74, one of the paddles 74 will be moved through the position tothe left side of FIG. 5, that is, with the plane of the paddle 74transverse to the direct-ion :of movement of the boat. As the paddle isforced through the water by the rotation of the housing 52 it will pushbackwardly on the water in the venturi throat and move the boatforwardly. As the paddle moves around the center shaft 54, it willrotate 180 degrees in one direction as the housing 52 rotates 360degrees in the opposite direction due to the ratio of the gearingprovided. Thus, as the paddles 74 move to the other positions shown inFIG. 5, the plane of the paddle will be changed so that the componentaction on the Water is always in the same direction. By driving thehousing on the periphery, and supporting it on rollers contacting theoutside surface, the overhung load is removed from the central shaft,thereby making the cycloidal propeller a practical and improved means ofpropulsion.

In practice, one power means can be used to drive both cycloidalpropelling means, or more than one of the power means can be used witheach propelling means. Suitable clutch means (not shown) are providedwith the power means in the common manner.

A drum 110 is provided and is secured to center shaft 54- in anysuitable manner, such as by providing a collar or plate 112 to which thedrum 110 is secured and the collar or plate 112 is in turn mounted onthe shaft 54. Drum 110 is positioned between the deck panel 30 and thetop 60 of housing 2, although in some instances the drum 110 can bemounted above the deck panel 30. Drum 110 is grooved as shown at 114.

An upright support 116 of suitable construction is mounted on the deckof the boat. The support carries a shaft 118 on which is mounted asteering wheel 120. Two drums 122 and 124 are mounted on the shaft 113to be turned by the steering wheel12l). Cables 126 and 128 are wound onthe drums 122 and 124 respectively. Cables 126 and 128 are wound inopposite directions on drums 122 and 124 so that when shaft 118 isturned by steering wheel 12!) one of the cables will be wound on thedrums and the other will be unwound.

Intermediate pulleys 130, 132, 134 and 136 are secured to the boat deckconstruction in any suitable manner. Cables 126 and 128 are received bypulleys 13%]- and 132 respectively and secured to the mounting means forpulleys 134 and 136 respectively.

Other cables 138 and 140 are provided and are received by the pulleys134 and 136 respectively. The cables 138 and 140 are secured to astationary pin or the like shown at 142 and 144. The other ends ofcables 138 and 140 are secured to opposite ends of an elongated helicalspring 146. The intermediate portion of cables 138 and 141) surround thepulleys 110 on the sculling drive means 50.

As will be seen from FIG. 3, when steering wheel 12!? is turned, shaft118 is rotated causing cables 126 and 128 to be reeled onto drums 122and 124 or therefrom. This movement of cables 126 and 128 causes drum-s134 and 136 to move, which in turn moves cables 14d and 138. As cables138 and 140 are moved, the drums 110' on the sculling drive means willbe rotated, causing the center shafts 54 to be turned. This turning ofthe center shafts 54 will move the relative position of the paddles 74in operation, causing a similar change in the direction of thepropelling force caused by the movement of paddles 74'. By turningsteering wheel 120' and rota-ting the center shafts 54, the direction ofthe propelling force of each of the sculling drive means 51 mounted onthe deck sections 24 and 28 can be changed in unison to provide thesteering mechanism for this boat means. By rotating the center shaft 180degrees the boat can be completely reversed.

It has been found that the sculling drive means as shown and describedhereinbefore is particularly suitable for use with a twin hull boatconfiguration as hereinbefore described. This is particularly so whenthe sculling drive means 50 is mounted so as to be received in endportions of the venturi passage approximately at the ends of the throatthereof formed by the contoured hulls. As the boat is moved through thewater, the contour of the hulls will concentrate the water between thehulls at the throat of the venturi formed by the hulls and the locationof the drive means adjacent ends thereof results in an efiicient andhighly economical boat and drive means construction. Pressuredifferential will propel the boat to the maximum efiiciency, arelatively low pressure being formed at the forward end of the craft anda relatively high pressure at the aft end.

The hull lines provided are generally parallel to the direction oftravel, providing for streamlined movement of the craft in the water andeliminating power losses occurring as a result of the wake created byconventional boat construction. The sculling propulsion means isoper-ably in the draft of the craft, and in operation increases thedesirable pressure differential.

As will be. evident to those skilled in the art, various modificationsof this invention can be made or followed, in the light of thisdescription and discussion, without departing from the spirit of thedisclosure or the scope of the claims.

What is claimed is: I

1. A boat comprising, in combination, two hulls, each of said hullsbeing hollow and formed of a molded, reinforced plastic material, ahoneycomb boat deck mounted on said hull and extending therebetween,said deck positioning said hulls in spaced, generally parallel relation,said hulls when mounted being the mirror image of each other andcontoured externally so that when mounted on said deck said hulls form aventuri passage therebetween, said venturi passage including a throatportion with straight parallel sides and enlarged end portions havingsides diverging [from ends of the throat portion toward respective endsof said boat, and scullingpropel- 'ling means centrally mounted in eachend portion of said deck and positioned in said end portions of saidventuri passage adjacent ends of the throat thereof, each of saidsculling propelling means having a normally stationary center shaftsupported from said deck in suspended relation, said center shaftsupporting a closed cylindrical housing above the venturi passage, saidcenter shaft journaled in said housing, three drive shafts, said driveshafts being rotatably journaled in said housing and projectingdownwardly therefrom, a paddle mounted on the lower end portion of eachof said drive shafts and positioned in the venturi passage, the planesof said paddles converging rat a single point, said drive shafts beingradially and equally spaced from said center shaft and from each other,an intermediate shaft between said center shaft and each of said driveshafts and journaled in said housing, planetary gearing mounted on saidcenter shaft, said intermediate shafts, and said drive shafts connectedand operable to turn said paddles, three spaced supporting wheelsmounted in said deck and engaging the side of said cylindrical housingto support same for rotation, an engine mounted on said deck adjacenttoeaoh of said sculling propelling means with the drive shaft thereofprojecting downwardly into said deck, and a V-bel-t connecting the driveshaft of said engine and the outer surface of said housing to turn saidhousing when said engine is in operation, a drum rigidly mounted on saidcenter shaft of each of said sculling propelling means between saidhousing and the top of said deck, an upright support mounted on saiddeck, a shaft carried by said support, a steering wheel mounted on oneend of said shaft, two drums mounted on the other end of said shaft, andcables connecting said drums on said propelling means with said drums onsaid shaft so that as said steering wheel is turned said center shaft ofeach of said propelling means is rotated, causing the direction of thepropelling force of said paddles to be correspondingly changed, saidboat being constructed and adapted so that said engine will rotate saidcylindrical housing causing 7 said drive shafts therein to he rotated todrive said boat in the water with said hulls having streamlined movementrelative to the water through said venturi passage, and

said steering Wheel can rotate said center shafts to change thedirection of thrust and turn said boat.

2. A boat comprising, in combination, two elongate hulls, a deck carried'by said hulls and extending the length thereof and extendingtherebetween to space the hulls in mirror image relation, said deckhaving a bottom surface with said surface between the hulls being planarfor the length thereof, said hulls being generally parallel and havingopposite outer planar sides parallel to the longitudinal center line ofthe boat, said hulls having inner adjacent sides contoured to cooperatewith said bottom surface of the deck to form an unobstructed venturipassage between said hulls, said inner adjacent hull sides havingsubstantially straight parallel planar portions forming a venturi throatand end portions on the respective hulls in diverging relation extendingfrom the venturi throat to respective ends of the hulls and formingenlarged entry and outlet portions of the venturi hulls, each of saidhulls being hollow, a deck carried by said hulls and extending thelength thereof and extending therebetween to space the hulls in mirrorimage relation, said deck having a bottom surface with said surfacebetween the hulls being planar for the length thereof, said hulls beinggenerally parallel and having opposite outer planar sides extending forthe length of the hulls and parallel to the longitudinal center line ofthe boat, said opposite outer sides being inclined downwardly andinwardly, said hulls having inner adjacent sides contoured to cooperatewith said bottom surface of the deck to form an unobstructed venturipassage between said hulls, said inner adjacent hull sides havingsubstantially straight parallel planar portions forming a venturi throatand end portions on the respective hulls in diverging relation extendingfrom the venturi throat to respective ends of the hulls and formingenlarged entry and outlet portions of the venturi passage, andpropelling means of cycloidal type having a housing rotatably supportedon said deck and a plurality of paddles depending therefrom and bodilyrotatable with said housing about a vertical axis, said propelling meansbeing arranged at one of said enlarged portions of said venturi passageadjacent said venturi throat with only the paddles extending below thebottom surface of the deck into said passage for propelling waterthrough said venturi passage and thus propel the boat in operation.

4. A boat comprising, in combination, two elongate hulls, each of saidhulls being hollow, a deck carried by said hulls and extending thelength thereof and extending therebetween to space the hulls in mirrorimage relation, said deck having a bottom surface with said surfacebetween the hulls being planar for the length thereof, said hulls beinggenerally parallel and having opposite outer planar sides extending forthe length of the hulls parallel to the longitudinal center line of theboat, said opposite outer sides being inclined downwardly and in wardly,said hulls having inner adjacent sides contoured to cooperate with saidbottom surface of the deck to form an unobstructed venturi passagebetween said hulls,

said inner adjacent hull sides having substantially straight parallelplanar portions forming a venturi throat and end portions on therespective hulls in diverging relation extending from the venturi throatto respective ends of the hulls and forming enlarged entry and outletportions of the venturi passage, propelling means of cycloidal typehaving a center shaft supported from the deck in suspended relation anda housing rotatable on said shaft with a plurality of paddles dependingtherefrom and bodily rotatable with said housing about a vertical axis,said propelling means center shaft being arranged at one of saidenlarged portions of said venturi passage adjacent said venturi throatwith only the paddles extending below the bottom surface of the deckinto said passage for propelling water through said venturi passage andthus propel the boat in operation, gear means operatively connectingsaid center shaft with said paddles for rotat- I ing said paddlesrelative to said housing in response to rotation of said housing, andmeans operatively connected to said center shaft for selectivelyrotating same in changing the relative position of the paddles to thehousing and direction of thrust of said paddles.

References Cited in the file of this patent UNITED STATES PATENTS126,701 Hilgerd May 14, 1872 392,346 Kirsch Nov. 6, 1888 1,172,892 LerroFeb. 22, 1916 1,740,820 Kirsten Dec. 24, 1929 2,091,264 Berry Aug. 31,1937 2,464,957 Wood Mar. 22, 1949 2,585,502 Schneider Feb. 12, 19522,837,049 Franz June 3, 1958 2,950,701 Stefaru' Aug. 30, 1960 FOREIGNPATENTS 2,093 Great Britain 1899 2,470 Great Britain 1906

2. A BOAT COMPRISING, IN COMBINATION, TWO ELONGATE HULLS, A DECK CARRIEDBY SAID HULLS AND EXTENDING THE LENGTH THEREOF AND EXTENDINGTHEREBETWEEN TO SPACE THE HULLS IN MIRROR IMAGE RELATION, SAID DECKHAVING A BOTTOM SURFACE WITH SAID SURFACE BETWEEN THE HULLS BEING PLANARFOR THE LENGTH THEREOF, SAID HULLS BEING GENERALLY PARALLEL AND HAVINGOPPOSITE OUTER PLANAR SIDES PARALLEL TO THE LONGITUDINAL CENTER LINE OFTHE BOAT, SAID HULLS HAVING INNER ADJACENT SIDES CONTOURED TO COOPERATEWITH SAID BOTTOM SURFACE OF THE DECK TO FORM AN UNOBSTRUCTED VENTURIPASSAGE BETWEEN SAID HULLS, SAID INNER ADJACENT HULL SIDES HAVINGSUBSTANTAILLY STRAIGHT PARALLEL PLANAR PORTIONS FORMING A VENTURI THROATAND END PORTIONS ON THE RESPECTIVE HULLS IN DIVERGING RELATION EXTENDINGFROM THE VENTURI THROAT TO RESPECTIVE ENDS OF THE HULLS AND FORMINGENLARGED ENTRY AND OUTLET PORTIONS OF THE VENTURI PASSAGE, ANDPROPELLING MEANS OF CYCLOIDAL TYPE HAVING A PLURALITY OF DEPENDINGPADDLES BODILY ROTATABLE ABOUT A VERTICAL AXIS, SAID PROPELLING MEANSBEING SUPPORTED ON SAID DECK ON THE CENTER LINE OF THE BOAT AT ONE OFSAID ENLARGED PORTIONS OF SAID VENTURI PASSAGE ADJACENT SAID VENTURITHROAT WITH ONLY THE PADDLES EXTENDING BELOW THE BOTTOM SURFACE OF THEDECK INTO SAID PASSAGE FOR PROPELLING WATER THROUGH SAID VENTURI PASSAGEAND THUS PROPEL THE BOAT IN OPERATION.